The present invention relates to novel fluorinated compositions, and more specifically, it relates to double-sequence compounds having a completely or partially fluorinated sequence and a hydrophilic hydrocarbon sequence, together with processes for preparing same, and use thereof as surfactants, especially in fire-fighting emulsifiers.
Perfluorinated compounds are well known for their ability to lower considerably the surface tension of liquids in which they are dissolved, even at very low concentrations. However, to be usable as surfactants in an aqueous medium, they must be made water-soluble. To this end, a hydrophilic group or sequence, which can be anionic, cationic, amphoteric or nonionic in nature, is added to the fluorinated chain. Such surfactants are well known. See, for example, R. E. Banks, "Organofluorine Chemicals and Their Industrial Applications", London: Ellis Horwood, Ltd., 1979, pages 214-234.
In the majority of fluorinated surfactants, the hydrophilic portion consists of a conventional chemical group such as a carboxylate, sulfonate, quaternary ammonium, or betaine group, and the like, but fluorinated surfactants are also known in which the hydrophilic portion is a hydrophilic oligomeric arrangement. Thus, in U.S. Pat. No. 2,723,999 there are described products corresponding to the formula: EQU C.sub.x F.sub.2 x+1 CH.sub.2 O--(C.sub.2 H.sub.4 O).sub.y H
with y being one to 200.
In U.S. Pat. No. 4,377,710, there are described products having the formula: ##STR1##
The main advantage of this type of surfactant comes from the possibility of easily varying their hydrophobic/hydrophilic balance. Moreover, European patent No. 19,584 describes the preparation of products of the type: ##STR2## where y can vary from four to 500 and X is particularly a COOH or CONH.sub.2 group, by free-radical telomerization of a thiol C.sub.x F.sub.2x+1 C.sub.2 H.sub.4 SH with a vinyl monomer such as, for example, acrylic acid or acrylamide.
The reaction of perfluoroalkyl iodides with olefins ##STR3## has, moreover, been very extensively studied, in particular by N. O. Brace, U.S. Pat. No. 3,145,222 and J. Org. Chem. 27, 3033 (1962); 27, 4491 (1962); and 32, 430 (1967). However, in the majority of cases, this reaction only provides a monoaddition product with y being one, and only certain highly reactive olefins give oligomers in which y is greater than one. Thus, ethyl acrylate provides a product with y equal to eight, and styrene a derivative with y being two. While the free-radical reaction of perfluoroalkyl iodides with olefins is known, the same does not, on the other hand, apply to the analogous reaction of derivatives of the type C.sub.x F.sub.2x+1 --CH.sub.2 I or C.sub.x F.sub.2x+1 --C.sub.2 H.sub.4 I.